Punching machine



March 18, 1952 H. OETIKER PUNCHING MACHINE Filed Aug. 17, 1948 4 a Z I aM w {D W"/ z W Z m u m J m m u r m I INVENTOR #AIYS fifTI/(f/E ATTORNEYPatented Mar. 18, 1952 UNITED STATES PATENT OFFliGE Application August17.1 948, serial No."44,739

In Switzerland August 1 8, .194?

Punching machines are known which are provided with a. puncher and dieand an automatically operating device for feeding the "work piece intothe machine. "These machines also "possess a device for the automaticejection of the punched-out work piece from the die. "Correct andreliable operation of the ejecting device is, however, of greatimportance because there is danger that when a punched-out piece"remains stuck in the die, the machine 'is not capable of withstandingthe increased pressure resulting from the next impact of the punchinghammer and bursts. The puncherand die are, however, relativel expensivemachine elements and ever ti'methey must be replaced it is necessary forthe machine to be put out of operation for some time and this results ina loss in production. since disturbances of this kind occur frequently,the output of the machine and its efliciently are considerably reduced.

The object of the invention is to eliminate the danger of the machinebeing destroyed or dams aged when the ejection device does not operateand "thus enable the punchin speed to be increased and thereby raise theoutput of the machine. I

The invention concerns a punching machine with a .puncher and die and anautomatically operating device for progressively ifeeding the work stripinto the machine, as well as a device forautomatically ejecting thepunched-out pieces from the die, a safety device being provided which,when the ejection device does not function, operates due to a change inthe stroke of the ejecting elements produced by the work piece which isstuck in the die, whereby this safety device brings the punching machineto a standstill.

The punching machine according to the invention is thus so constructedthat it protects itself against destruction. Once the machine has beenstopped, it is an easy matter to remove the jammed work piece from themachine and to start up the latter again. The most important feature ofthe new machine is. however, that due to the automatic safety device themachine can be operated at a much higher speed than machines which donot have this self-protective device.

A constructional example of the invention is shown diagrammatically inthe accompanying drawing, Figs. 1 to 3 illustrating various operastional phases of a punching machine according to the invention.

The punching machine shown in the figures 2 Claims. (Cl. 164-10 5) 2 has.an ejecting device comprising an ejection piston I, an ejection pm 2.and a lever '3. 'Inaill three figure's, numeral '4 designates thepunching hammer which is moved rhythmically up and down 'by the plunger5. Numeral '6 designates a die fixed to the hammer 4. Numeral ldesignates apuncher mounted on a baseplate. The ejection piston '1slides freely'inside'the die 6 and lever 3 pivo'tally supported at 8serves as afstopifor the ejection pin. Numeral 3 designates (a "springwhich presses the supporting :ring "In againstthe work strip H.

The work strip H "which is to be punched moves between guide rollers and"is moved gradually forward after each punching operation by a'feedmechanism not shown in the drawing.

At the end of lever 3 is a set screw I! which is in contact with theleft-hand end of a beam 13 pivoted at M. The right-hand end of beam 13rests on one end of a contact lever lipivdted at 1'6, the other end ofthis contact lever lying on the contact 11. Thepivots l4 and I6, as wellas the contact l1 are mounted on the frameor arm 1'8 which is rigidlyconnected with the punching hammer 4. Contact lever .15 and contact Hare connectedto an electric circuit which is supplied from a battery l9,the current from this circuit being. used to excite a magnet v20 whosearmature 21 is attracted against the fierce of a spring 22. The armature21 can swing about the fixed axis 23 and'is provided at its upper end,which .is bent atright angles. with a pawl which engages the-latch .2 4that is pressed against the pawl by a spring 25. When the latch {isreleased, the rod which is connected with {it jumps to the right underthe action of the spring 25 and .puts a conventional mechanism, -.not

shown in the -drawing,'into'operation thusbringing the punching machinevery quickly to a f standstill. The movement 50f the actuating lever 3in an upward direction is limited by a set screw 26 mounted on astationary support.

Fig. 1 shows the position of the various elements of the machine beforethe commencement of a normal punching operation, the ejection elementsbeing in their normal initial position. The ejection pin 2 and thepiston I are in their lowest positions. If the punching hammer 4 is nowmoved downwards by the plunger 5, a piece Z'l'is punched out of the work'stripll and pushed into the space inside the die 6, as shown in Fig. 2.The ejection pin 2 is now moved out of its initial position by an amountequal to the thickness of the punched-out piece 21,

but this displacement is not sufficient to displace thickness of thework strip.

. position by coming into contact with the stationary set screw or stopmember 26. The lever 3 which acts as stop for the ejection pin thereforepushes the latter back into its initial position, whereupon the piece 21is expelled from the die. By means of a blower which is not shown it ispossible to remove the piece 21 entirely from the machine.

In practice, it frequently happens that the work piece is-not completelyexpelled and reains stuck in the, die, so that for the nextpunchlingoperation the ejection pin has a different starting position.This case is illustrated in Fig. Thepunching hammer when moving downhas'punched out a further piece 28 and now the -twofpieces 21 and Barestuck in the die one above the other. The ejection pin 3 is thusdisplaced upwards by an amount equal to the double accordance with theinvention, the device is so constructed that the displaced ejection pinnow turns the lever 3 about its pivot 8. This causes the set screw l2 onlever 3 to change the position of beam I3, whereupon contact lever l5swings about'pivot 16, so that contact lever I5 is no longer in contactwith contact [1. electric circuit of the battery I9 istherefore'interrupted by the opening of thes contacts. Holding magnet isnow no longer excited and spring 22 pulls the armature 2| away from themagnet.

The armature revolves about the axis 23' and releases the latch member24 'whose rod actuated by the spring 25 sets the conventional mechanisminto operation which immediately stops the punching machine, so that thepieces 2'! and 28 which are stuck in the die can be removed.

In'the constructional example described above, "an electrical circuit isused which operates with a" continuous current. It is, however, alsopossible to utilize acircuit which is interrupted dur--inglnormalservice-and closed when a disturbance occurs. Instead of anelectric current it is also possible to use a-fiowingmedium, such ascompressed air, oil-,- or the like, for actuating the mechanism whichbrings the machine to a stand still. 1 In a similar manner it is alsopossible to provide a purelymech'anical system such as a systemof'levers actuated by springs. In "order that the machine should come toa standstill as soon as possible, it is expedient to The disconnect itfrom its driving motor and subject it to a braking action.

With punching machines where the punchedout pieces are conveyed awayfrom the machine by air blasts from a blower, it is an advantage toprovide means which, when the machine is brought to a standstill, at thesame time out ofi the air supply, so that there is no waste ofcompressed air.

I claim: 1. A punching machine for punching substantially flat workpieces from strip-like work material, comprising means for continuouslyfeeding the work material into the machine, a stationary puncher, areciprocatingly movable punching hammer having a cavity receiving saidpuncher, piston means slidable in said cavity and displaceable by thepunched work pieces resting on said puncher, a lever pivoted to saidreciprocatingly movable punching hammer, a stationary abutment placed inthe path of said lever to be abutted by said lever when said punchinghammer approaches the end of its idle stroke,

said lever being swingable in a plane containing the longitudinal axisof said piston means and abutting against the latter upon abutment ofsaid lever against said stationary abutment and tending topush saidpiston means out of said cavity during the rest of the idle stroke ofsaid punching hammer to effect the ejection of a punched-out piece, anelectric switch mounted on said punching hammer to move therewith andpositioned relative to said lever to be actuated thereby upon abutmentof said piston means against said lever upon improper displacement, dueto the failure of a punched-out piece to be ejected by the action of thestationary abutment, of said piston in said cavity, and stop means forstopping the punching machine connected with and controlled by saidswitch.

2. A punching machine as defined in claim 1,

said stop means comprising a latch member, a

spring urging said latch member into position for :stopping the machine,and an electric circuit ineluding and being exclusively controlled bysaid REFERENCES CITED The following references are of record in th fileofthispatent: I

UNITED STATES PATENTS Number Name Date 2,134,933 Smith Nov. 1, 19382,200,886 Kuhn May 14,1940

